Characterization and modeling of InGaAs/GaAs multi-quantum well lasers by capacitance-voltage measurements
Charakterisierung und Modellierung von InGaAs/GaAs Mehrfach-Quantenfilm Laserdioden durch Messung der Kapazitätsspannungs-Abhängigkeit
We have measured and analyzed the room-temperature capacitance-voltage (C-V) characteristics of In(0.35)Ga(0.65)As/GaAs MQW laser structures with different doping levels in the active region. Average doping densities in the well-barrier regions were directly extracted from the as-measured carrier profiles. A model for the C-V measurements, including the self-consistent solution of Poisson and Schrödinger equations, was developed. The carrier profiles obtained from the simulated C-V characteristics do not correspond to the free carrier profiles since the local charge neutrality hypothesis does not hold for QW structures. Thus, the true carrier distribution can only be determined from a full quantum-mechanical simulation of the laser structure. We have determined, from the comparison between experimental and simulated profiles, a conduction band offset delsta E(c)/delta E(g) of 0.81. We have also applied C-V measurements to samples with interdiffused QWs, and obtained the characteristic interdiffusion length.